Regensburg 2002 – scientific programme
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CPP: Chemische Physik und Polymerphysik
CPP 11: Dünne Filme, Monolagen und Oberfl
ächen
CPP 11.7: Talk
Wednesday, March 13, 2002, 15:30–15:50, H38
AFM study of photostimulated structural changes of liquid crystal surfaces — •Bianca Gabel1, Carola Kryschi1, Slava Dremov2, Vladimir Popov2, and Paul M"uller2 — 1Institut f"ur Physikalische Chemie I, FAU, Egerlandstr.3, 91058 Erlangen — 2Lehrstuhl f"ur Experimentalphysik III, FAU, Erwin-Rommel-Str.1, 91058 Erlangen
The surface morphology and optical properties of liquid crystal films doped with photochromic dithienylethene compounds are shown to be reversibly altered by photoirradiation. The photo- switching between two optical and structural states is based on the photochromism of the dithienylethene dopant which may exist as an open or as a closed isomer. While the open isomer has a twisted structure and exhibits an absorption spectrum in the uv, the absorption spectrum of the nearly planar closed isomer is shifted into the visible range. Photostimulating either the ring closure or the ring opening reaction is associated with large structural changes which may induce a phase transition of the liquid crystal matrix. The photoresponse of the surface morphology of different photochromic liquid crystals to uv and visible light has been mapped by atomic force microscopy.